linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Arvind Sankar <nivedita@alum.mit.edu>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] x86/cmdline: Disable instrumentation of cmdline unconditionally
Date: Sun,  6 Sep 2020 11:46:37 -0400	[thread overview]
Message-ID: <20200906154637.1618112-1-nivedita@alum.mit.edu> (raw)

On 32-bit, cmdline_find_option_bool() is used before paging is enabled,
from check_loader_disabled_bsp() in the early microcode loader.
Instrumentation options that insert accesses to global data will likely
crash or corrupt memory at this point.

cmdline_find_option{,_bool}() are only used during boot, so
instrumentation is not that useful anyway.

Disable instrumentation unconditionally, and additionally disable:
- GCOV
- UBSAN
- tracing: change -pg -> CC_FLAGS_FTRACE
- STACKLEAK_PLUGIN
- BRANCH_PROFILING

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
 arch/x86/lib/Makefile | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index aa067859a70b..0ad4ae9def44 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -15,17 +15,19 @@ CFLAGS_REMOVE_delay.o = $(CC_FLAGS_FTRACE)
 endif
 
 # Early boot use of cmdline; don't instrument it
-ifdef CONFIG_AMD_MEM_ENCRYPT
+GCOV_PROFILE_cmdline.o    := n
 KCOV_INSTRUMENT_cmdline.o := n
 KASAN_SANITIZE_cmdline.o  := n
+UBSAN_SANITIZE_cmdline.o  := n
 KCSAN_SANITIZE_cmdline.o  := n
 
 ifdef CONFIG_FUNCTION_TRACER
-CFLAGS_REMOVE_cmdline.o = -pg
+CFLAGS_REMOVE_cmdline.o = $(CC_FLAGS_FTRACE)
 endif
 
 CFLAGS_cmdline.o := -fno-stack-protector -fno-jump-tables
-endif
+CFLAGS_cmdline.o += $(DISABLE_STACKLEAK_PLUGIN)
+CFLAGS_cmdline.o += -DDISABLE_BRANCH_PROFILING
 
 inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk
 inat_tables_maps = $(srctree)/arch/x86/lib/x86-opcode-map.txt
-- 
2.26.2


             reply	other threads:[~2020-09-06 15:47 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-06 15:46 Arvind Sankar [this message]
2020-09-17  9:40 ` [PATCH] x86/cmdline: Disable instrumentation of cmdline unconditionally Borislav Petkov
2020-09-17 16:05   ` Arvind Sankar
2020-09-17 17:28     ` Borislav Petkov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200906154637.1618112-1-nivedita@alum.mit.edu \
    --to=nivedita@alum.mit.edu \
    --cc=linux-kernel@vger.kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).